Breakaway switch devices have long been used to detect the unintended separation of a pair of mutually coupled vehicles or other such machines, for example, the separation of a towed vehicle from a towing vehicle such as a trailer and an automotive vehicle pulling the trailer. Various different forms of such devices have been used or considered over time, but the most widely accepted type is one which uses a xe2x80x9cpull-pinxe2x80x9d or the like that is connected to the towing vehicle and normally carried in an inserted position in a switch housing mounted on the trailer, in which position the pin is disposed between a pair of electrical contacts located inside the housing, to prevent them from contacting one another and allowing current to flow through them. Since the pin is connected to the towing vehicle, the accidental decoupling of the towed vehicle will immediately pull the pin out of the switch housing, allowing the electrical contacts to touch and thereby complete an electrical circuit that can actuate an alarm and/or provide some other such desired result, including the application of brakes on the towed vehicle, as an automatic response.
Many or most such breakaway switch devices used in the past have included electrical contacts that are either attached to or comprise an integral part of long, specially shaped blade-type electrically conductive members which not only carried the electrical contacts but also acted as springs. These were specially mounted and retained inside a switch housing so that their end extremities or other contact portions would normally be spring-biased into mutual contact were it not for the pull-pin actuator, which when inserted pushed the two self-biased spring contacts apart to prevent their engagement and thereby maintain the same in open-circuit configuration until the pin was withdrawn.
Switch assemblies of the type just described are expensive to produce since the long spring-type electrical contacts are relatively expensive to manufacture, and they are also difficult and labor-intensive to assemble within the switch housing, as they do not lend themselves to automated assembly and typically require manual assembly. Furthermore, they often do not provide optimal switching operation due to their size, shape, and manner of operation, and are often subject to exposure to the elements, since their corresponding switch housings may not be well sealed. Consequently, the switch contacts may rust and corrode over time, sometimes becoming unreliable and even inoperative at the time upon when they are finally needed. In addition, such spring-contacts may lose their resiliency over time and are also subject to distortion by bending in use, due to the insertion and withdrawal of the pull-pin actuator each time a trailer is coupled and uncoupled. Numerous other disadvantages also attended the use and manufacture of such switch assemblies.
The present invention provides a unique and effective solution for problems such as those noted above in connection with previous types of breakaway switches, providing a new type of breakaway switch assembly of high reliability and long life which is at the same time extremely economical to manufacture and also easy to use.
In a first aspect, the breakaway switch assembly comprises a housing enclosure having a self-contained switch unit disposed inside it which has an internal switch mechanism and an externally accessibly operating member. The self-contained switch unit has an outer body with mounting surfaces that engage switch-retention members inside the housing enclosure to hold the switch unit in predetermined placement therewithin. Input and output conductors are connected to corresponding terminals of the switch unit to carry an electrical current which is switched through the switch unit, such signal conductors extending out of the housing enclosure. An externally accessible actuator extends into the housing enclosure in alignment with the switch-operating member of the switch unit, and the actuator is movable from at least a first position to a second position whereby it moves the switch-operating member into and out of a position causing electrical conduction through the switch unit.
In a preferred embodiment, the self-contained switch unit to be mounted inside the housing enclosure comprises a standard off-the-shelf push-button or rocker-type switch, with integral flanges or the like which are rapidly and easily insertable into place between opposing such flanges provided inside the housing, and the switch unit includes spade-type or other such quick-connect electrical terminals extending from it, by which the electrical conductors used to form the related electrical circuit may be quickly and easily connected to the switch unit during manufacture. In addition, a preferred pull-pin actuator for the assembly comprises an integral one-piece member, preferably molded of non-conductive or other such polymer, to provide a very economically manufactured member of high reliability and easy utilization, and having a structural configuration which includes a portion for directly engaging the switch unit operator (push-button or rocker), to hold it in predetermined position actuating the switch in a desired manner dependent upon the position of the pull-pin.
The foregoing general and preferred attributes of the invention will become increasingly apparent and better understood following consideration of the ensuing specification and claims, taken in conjunction with the attached drawings.